1. Field of the Invention
The present invention relates to an improved method of ion exchanging a crystalline zeolite.
2. Description of the Prior Art
It is well known to exchange a cation of a crystalline zeolite with another cation by aqueous or non-aqueous methods.
U.S. Pat. Nos. 3,875,290 and 3,948,760 disclose ion exchanging a crystalline aluminosilicate zeolite with an ammonium ion to produce a partially exchanged ammonium aluminosilicate zeolite and subsequently contacting the partially ammonium exchanged aluminosilicate zeolite with a nitrogen compound, which may be urea, and a water soluble salt of a polyvalent metal such as Al, Zr, or Cr to produce, after calcination, a hydrogen and metal exchanged crystalline aluminosilicate which is suitable for use as catalyst in catalytic hydrocarbon conversion processes.
It has now been found that an ion exchange medium comprising an ammonium ion and urea can be used to advantage in ion exchanging an alkali metal metallosilicate zeolite.